A conventional display device is known, which is described in Patent Literature 1. The display device (lighting device) of Patent Literature 1 includes a sector-shaped dial having numeric characters and scales formed in the circumferential direction, a substrate arranged at the back side of the dial, light sources (LED) arranged on the substrate in the circumferential direction, and a light introducing object interposed between the dial and the substrate to lead the light from the light source to the dial.
RGB full color LED is used as the light sources. Blue, green, yellow, orange and red lights are emitted in this order from the small numeric character side towards the large numeric character side in the circumferential direction of the dial. When the light sources are turned on, the luminescence forms a gradation on the dial.